Determination and Correlation of Solubility of Metformin Hydrochloride in Aqueous Binary Solvents from 283.15 to 323.15 K.

Metformin hydrochloride (MET·HCl) is one of the most widely used oral hypoglycemic drugs in the world. In addition to hypoglycemic effects, MET·HCl also has anti-inflammatory, anti-tumor, anti-aging, and other effects, showing good efficacy and safety of single and combined treatment. The solubility of MET·HCl in water, water + ,-dimethylformamide, water + acetonitrile, and water + -propanol was measured by the gravimetric method under atmospheric pressure at temperatures ranging from 283.15 to 323.15 K. The solubility of MET·HCl has a positive correlation with temperature and water content. The experimental solubility data in binary solvents was correlated by the modified Apelblat model, CNIBS/R-K model, Apelblat-Jouyban-Acree model, and λ model. By comparing the average ARD % values of the four models, it is found that the modified Apelblat model (ARD % = 1.26) provides better correlation. Hansen solubility parameters and apparent thermodynamic parameters were calculated to analyze the solubility behavior, indicating that the dissolution process is endothermic and entropically favorable.